Toughened biodegradable composites

For several years now, the field of sustainability has given rise to a sharp increasing interest from scientists and industrials. The ideal products that could address all problems such as economics, environment and social responsibility have been under survey. From economics’ point of view the new product should have ability to compete with other products in some areas such as production cost, properties and on the other hand, it should be answer avoiding environmental damage. Renewable resource based bioplastics offer a vast and new area to start researching fundamentally on replacing or decreasing resources (specially fossil fuels) used for conventional plastic applications. The demand in designing materials with novel functionalities is growing for many applications. Since the mechanical properties of bioplastics can be compared with other commercial plastics like PE, PS, and therefore it has large opportunities to substitute these polymers for numerous applications. However, some disadvantages prevented bioplastics from being used in vast area. In this project, main focus would be on toughening bioplastics with avoiding of sacrificing other mechanical properties.

Fracture toughness of the nanoparticles modified CFRP

Previous work has showed that the nanoparticle reinforced epoxy has some priorities on the fracture performance. Thus, it is reasonable to expect that the nanoparticles can improve the delamination resistance of carbon fiber reinforced polymer (CFRP) when they are added to the matrix resin. In this project, the interlaminar fracture toughness of the nanoparticles modified CFRP will be tested and the toughening mechanism will also be studied.

Our work aims at understanding the mechanisms of Lamb wave propagation in sandwich CF/EP composite structures and developing algorithms to detect and assess de-bonding between the surface composite panels and the core (Honeycomb). Piezoelectric elements that are bonded on the surface of the structure will give us information on the nature of the damage within the structure. We will use the transmitted and reflected wave signals from the PZT elements after interacting with de-bonding damage and further analyze that to extract all the useful information which help us position and estimate the severity of the damage. The work is divided into two parts: (i) experimental and (ii) numerical simulation. Finite Element Analysis using ABAQUS is used to support our investigation and fulfill the second part of the work.

The toughening and strengthening mechanisms of epoxy nanocomposites modified by inorganic nanoparticles

The research covers a systematic investigation into the mechanisms of the toughening and strengthening effects of inorganic nanoparticles, such as nanosilica, halloysite, carbon nanotubes, and MMTs, on the mechanical performance of the cured epoxies. Mechanical characterizations are conducted to clarify the effects of the particles to the resultant composites. The mechanisms of toughening and strengthening effects of inorganic nanoparticles in epoxies are also be identified.

Blood-biomaterial interaction

The investigation of biochemical processes such as blood protein interactions with synthetic biomaterial surfaces is essential for making advancements in the biocompatibility of medical devices. The adsorption of proteins onto synthetic biomaterial surfaces is a fundamental factor that dictates host-biomaterial response. Synthetic biomaterial surfaces adsorb specific plasma proteins that form a proteinacious layer which mediates the adhesion and activation of platelets and the clotting cascade, and consequently the formation of blood clots. This may ultimately lead to the rejection of the material and subsequently, the implanted medical device. Recent work suggests that the conformation, activation and biological responses of adsorbed proteins are controlled by the chemical and topographical properties of the surfaces. Currently the preferential adsorption of a specific proteins, their exact interaction and the mechanisms of unfolding at the solid-liquid interface is still poorly understood due to the many factors which that influence these dynamic events. The exact mechanism behind protein unfolding and adhesion also remains unknown. Therefore the purpose of this project is to study the effect of surface properties using a range of metallic surfaces with controlled changes in surface chemistry and topography on the adsorption of plasma proteins and platelets in vitro.

Optimising bone tissue engineering by manipulation of anabolism and catabolism

Large bone defects are commonly treated with autogenous bone grafting (autografting). The graft material is harvested from the patient’s hip bone and transferred to the defect site. Despite common practice, autografting may result in donor-site pain, and possible fracture, nerve damage and infection. Current developments in the fields of bone tissue engineering (BTE), orthopaedics and biomaterials offer novel and exciting solutions in the search of alternative bone substitutes for the treatment of large bone defects. To date, published in vivo bone tissue engineering (BTE) systems are often in mechanically unloaded environments, leading to the premature resorption of newly formed bone. We propose to optimise bone formation by manipulating the effects of bone formation and bone resorption with clinically used bone drugs, bone morphogenetic protein (BMP), and bisphosphonate (BP). Bone formation was induced by insertion of BMP-loaded biodegradable polymer implant into a hindlimb muscle pouch. BP was then delivered to augment bone formation by preventing premature bone resorption (in a mechanically unloaded environment). To further optimise bone formation, we tested different polymer implant systems and compared methods of BP delivery. Bone formation in newly formed bone nodules were assessed with radiographic x-ray, micro computed tomography, and histological analysis. Results thus far support the development of more advanced BTE models of co-delivery BMP and BP for clinical use.

Direct bonding of PEEK by plasma treatment for encapsulation of medical implants

New high performance polymers have been developed that challenge traditional encapsulation materials for permanent active medical implants. The gold standard for hermetic encapsulation for implants is a titanium enclosure which is sealed using laser welding. The ability to create a hermetic join with an extended life remains the barrier to widespread acceptance of polymers for this application. The project aims to develop direct bonding of polymeric biomaterial PEEK for hermetic encapsulation of medical implants used in-vivo without the use of adhesives. Surface modification of PEEK will be conducted through PIII plasma treatment in order to achieve better bonding.

Computational design and fabrication of cellular materials and structures

I'm currently investigating biomimetic materials inspired by cuttlebone. Cuttlebone possess both high stiffness and high porosity - a desirable combination in many engineering applications. The basic aim is to determine the material properties of cuttlebone, and then design materials possessing these same properties. Cuttlebone has previously been used directly to create tissue scaffolds and superconducting materials. The new biomimetic materials will be investigated in these and other applications.

Design and analysis for biodegradable synthetics in computational tissue engineering

In the therapeutic tissue engineering, to avoid a time-consuming trail-and-error experimental process, computational simulation has been proved significant in predicting the material behaviors, dynamic responses and biomechanical processes. The synthetic scaffold, as a biomechanical support to the neo-tissue, plays an important role in tissue regeneration. However, clinical failures can be prevalently observed due to multifarious limitations of tissue scaffold used nowadays. In this regard, how to design the scaffold architecture and simulate a series of mechanical and biochemical processes including scaffold degradation, tissue regeneration and neo-vascularization becomes particularly momentous.

In situ straining and nanoindentation deformation in TEM of nanostructured (ns) materials

This project aims to investigate dynamic deformation processes in real time and extract the deformation mechanisms responsible for the high strength and high ductility found in some ns materials by the technique of in-situ straining and nanoindentation deformation in TEM.

This project aim to apply in-situ nanoindentation and tensile staining transmission electron microscopy (TEM) techniques to understand the deformation behaviour of nanostructured (ns) silicon carbide (SiC), to indentify the deformation mechanisms that contribute superhardness and good ductility/toughness and to study the composition and microstructures that enable the deformation mechanisms. The results extracted from the investigation will be used to guide the structural design of ns SiC thin films with superhardness and reasonably good fracture toughness.

This project aims to investigate the deformation mechanisms and mechanical properties of nanomaterials using in-situ deformation TEM. It will focuses on (1) the effect of nano scale materials dimensions on the mechanical properties of the materials including strength and ductility and (2) the deformation mechanisms responsible for the mechanical properties.